S9§ STUDIES IN FOSSIL BOTANY 



respects the Bennettitales appear to be more primitive 

 than the sister class. It has been suggested by Dr. 

 Wieland that in Triassic times there may not yet 

 have been any definite border-line, between the two 

 classes, so far as vegetative features are concerned. 1 

 In Anomozamites minor ( Williamsonia angustifolia of 

 Nathorst), the oldest known member of the Bennettitales, 

 the habit was equally unlike that of typical Cycadaceae 

 and of typical Bennettiteae. It has recently been 

 suggested that an abortive bud occurring beneath 

 the peduncle of the cone in the recent Cycad Dioon is 

 the second lateral branch of the primitive dichasium, 

 an interpretation which would tend to bring the 

 Cycadaceous morphology a step nearer to the type 

 of Anomozamites? 



On the other hand, the fructifications are on a far 

 higher level of complexity in the Bennettitales. The 

 lateral, probably axillary position of the fertile shoots 

 (flowers) is the first difference to be noted. As Dr. 

 Wieland puts it (p. 229), the Bennettitales have seized 

 on the lateral bud as a means of fructification, thus 

 ensuring the production of more numerous strobili. 

 That the axis of the inflorescence is a modified branch 

 of the stem is clear ; the enveloping bracts are, no doubt, 

 modified leaves or possibly leaf- bases, and likewise 

 present no difficulty. We might well compare them 

 to the scale-leaves, in which the young cone of an 

 ordinary Cycad is enwrapped. It is when we come 



1 American Fossil Cycads, p. 228. The author gives a very full com- 

 parison between the two groups, as regards both vegetative and reproductive 

 characters, in his Chapter IX. 



2 F. W. South and R. H. Compton, '• Anatomy of Dioon edn/e,'' A"dw 

 Phytologist, vol. vii. Dec. 1908, p. 225. 



